ok guys and gals iam at witts end with this 2007 duramax 6.6 lb7. so to begin I had this truck dropped off to me requesting a cp3 and injectors be installed after someone put old fuel in it after replacing left head full set of injectors and cp3 pump. I went to prime fuel system truck wont stay cranking it cranks for 1/2 sec to a second and kicks out. I have been trying to figure out what is causing this. I found that if crank shaft sensor is unplugged it cranks fine all fuses are good relay swaped no change. negative battery cables replaced no change found there was no gear indication on dash replaced saftey switch no change wires are good batterys are new and test good replaced crank and cam shaft sensor only one code pops up after scan and thats fuel temp sensor high voltage replaced fuel temp sensor and pigtail no change. checked and cleaned all grounds. am i missing something besides a bad tcm???